Question 1

Which of the following statements best explains why the first step of electrophilic aromatic substitution (EAS) is the rate-determining step?

Accepted Answer

It involves the loss of aromaticity, which is highly unfavorable and requires a large input of energy ($$\Delta G$$^{\ddagger}$$ is large).

Question 2

During the bromination of benzene, what is the role of $$\mathrm{$$FeBr_3$$}$$?

Accepted Answer

It acts as a Lewis acid to generate the electrophilic bromine species ($$\mathrm{Br^+}).$$

Question 3

Which of the following is the correct electrophile in the nitration of benzene?

Accepted Answer

The nitronium ion ($$\mathrm{NO_2$^+})$$

Question 4

Which of the following groups is a meta-director in electrophilic aromatic substitution?

Accepted Answer

$$\mathrm{NO_2$}$$

Question 5

Why do Friedel–Crafts alkylations often result in polyalkylation?

Accepted Answer

The first alkyl group introduced activates the ring toward further substitution.

Question 6

Which of the following statements about Friedel–Crafts acylation is correct?

Accepted Answer

Polyacylation does not occur because the acyl group deactivates the aromatic ring to further substitution.

Question 7

A student attempts to perform a Friedel–Crafts alkylation using chlorobenzene and $$\mathrm{$$AlCl_3$$}. $$What is the expected outcome?

Accepted Answer

No reaction occurs because aryl halides do not form carbocations readily.

Question 8

Which of the following best describes the effect of an electron-donating group (EDG) on the rate of EAS?

Accepted Answer

EDGs stabilize the transition state and the arenium ion, lowering $$\Delta G$$^{\ddagger}$$ and increasing the reaction rate.

Question 9

Which of the following is a limitation of Friedel–Crafts alkylation reactions?

Accepted Answer

Carbocation rearrangement can lead to mixtures of products.

Question 10

In the sulfonation of benzene, which condition favors the reverse (desulfonation) reaction?

Accepted Answer

Dilute sulfuric acid (high water concentration)

Question 11

Which of the following best explains why halogens are ortho-para directors but deactivating in EAS?

Accepted Answer

Their lone pairs can donate electron density by resonance (ortho-para directing), but their electronegativity withdraws electrons inductively (deactivating).

Question 12

A chemist wants to synthesize para-nitroaniline from aniline. Which strategy is most appropriate to avoid ring destruction during nitration?

Accepted Answer

Protect the amino group by acetylation before nitration.

Question 13

Which of the following is the correct order of reactivity toward EAS (from most to least reactive)?

Accepted Answer

Aniline $$\u003e$$ Toluene $$\u003e$$ Benzene $$\u003e$$ Nitrobenzene

Question 14

Which of the following is a correct statement about the Clemmensen reduction?

Accepted Answer

It reduces phenyl ketones to methylene ($$\mathrm{CH_2$}) $$groups.

Question 15

Which of the following best explains why the methyl group in toluene is an ortho-para director?

Accepted Answer

It stabilizes the arenium ion intermediate by inductive electron donation.

Question 16

Which of the following is the major product when nitrobenzene is nitrated?

Accepted Answer

Meta-dinitrobenzene

Question 17

A chemist wants to synthesize ethyl phenyl ketone from benzene. Which sequence of reagents is most appropriate?

Accepted Answer

$$\mathrm{CH_3CH_2COCl}$$, $$\mathrm{$$AlCl_3$$}$$

Question 18

Which of the following best describes the effect of a nitro group on the rate and orientation of EAS?

Accepted Answer

It is a strongly deactivating, meta-directing group.

Question 19

Which of the following is a correct statement about the sulfonation of benzene?

Accepted Answer

It is an equilibrium reaction and can be reversed by using dilute sulfuric acid.

Electrophilic Aromatic Substitution and Reactivity of Aromatic Compounds

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